1. Field of Invention
The present invention relates to a gamma calibrating circuit of a display. More particularly, the present invention relates to a programmable gamma calibrating circuit of a display.
2. Description of Related Art
Human eyes are more sensitive to variations in brightness in a dark environment which indicates that the brightness sensitivity of human eyes is non-linear. Therefore, a correction process, i.e., gamma correction, for correcting the brightness of an image displayed on a display is required so that the brightness is in accordance with the brightness found in the natural environment. A programmable gamma circuit is typically arranged in an LCD display device to generate gamma calibration signals for use in image gamma calibration, and the brightness correction process is implemented through a digital-to-analog converter which converts digital codes to analog voltages.
In general, digital-to-analog converters convert digital image signals into analog voltages having corresponding gamma characteristics. The bit width of these digital-to-analog converters is increased to obtain a desired gamma characteristic, and such increasing in the bit width of digital-to-analog converters causes an increase in the circuit area of the same. Particularly, in a high voltage process, resistor strings of the digital-to-analog converters require a large circuit area, and the circuit size as well as the production cost of the digital-to-analog converters are raised as a result.